Ceramic copper circuit board and method for manufacturing the same

ABSTRACT

A ceramic copper circuit board according to an embodiment includes a ceramic substrate and a first copper part. The first copper part is bonded at a first surface of the ceramic substrate via a first brazing material part. The thickness of the first copper part is 0.6 mm or more. The side surface of the first copper part includes a first sloped portion. The width of the first sloped portion is not more than 0.5 times the thickness of the first copper part. The first brazing material part includes a first jutting portion jutting from the end portion of the first sloped portion. The length of the first jutting portion is not less than 0 μm and not more than 200 μm. The contact angle between the first jutting portion and the first sloped portion is 65° or less.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of International Patent ApplicationPCT/JP2019/019294, filed on May 15, 2019. This application also claimspriority to Japanese Patent Application No. 2018-094521, filed on May16, 2018, and Japanese Patent Application No. 2018-231855, filed on Dec.11, 2018. The entire contents of which are incorporated herein byreference.

FIELD

Embodiments described herein relate generally to a ceramic coppercircuit board and a method for manufacturing the same.

BACKGROUND

The output of power modules mounted in industrial devices is increasingin recent years with the higher performance of industrial devices.Accordingly, the output is increasing for semiconductor elements. Theguaranteed operating temperature of a semiconductor element is about150° C. The guaranteed operating temperature of some high-performancesemiconductor elements has increased to about 175° C.

Accordingly, heat-resistant characteristics are desirable also forceramic circuit boards on which the semiconductor elements are mounted.The heat-resistant characteristics of a ceramic circuit board areevaluated by a TCT (thermal cycle test). The TCT is a technique thatevaluates the durability of the ceramic circuit board in which lowtemperature→room temperature→high temperature→room temperature is onecycle.

A ceramic copper circuit board that has excellent TCT characteristics isdiscussed in International Publication No. 2017/056360 (PatentLiterature 1). In Patent Literature 1, the TCT characteristics areimproved by controlling the length, the height, and the hardness of ajutting portion of a brazing material. Also, in Patent Literature 1, theTCT characteristics are improved by providing a sloped structure in ametal plate side surface.

Power density is an index of the performance of a power module. Thepower density of a module is determined by power density=VM×IM×n/Mv. VMis the rated withstand voltage (V). IM is the rated current atΔTj−c=125° C. (A). n is the number of semiconductor elements inside themodule. Also, My is the volume (cm3) of the module.

To increase the power density of a power module, it is necessary toincrease the number of semiconductor elements inside the module orreduce the volume of the module. Therefore, for a ceramic circuit board,it is desirable to mount more semiconductor elements in a smallerregion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view showing structure example ofa ceramic copper circuit board;

FIG. 2 is a schematic cross-sectional view showing a structure exampleof side surface shapes of a first copper part and a second copper part;

FIG. 3 is a schematic cross-sectional view showing another structureexample of the side surface shapes of the first copper part and thesecond copper part;

FIG. 4 is a schematic cross-sectional view showing another structureexample of the side surface shapes of the first copper part and thesecond copper part;

FIGS. 5A, 5B, and 5C are drawings showing a method for measuring theupper end portion of the first sloped portion and the angle of the upperend portion of the second sloped portion;

FIG. 6 is a schematic cross-sectional view showing another structureexample of the side surface shapes of the first copper part and thesecond copper part;

FIGS. 7A and 7B are schematic plan views showing structure examples ofthe ceramic copper circuit board;

FIG. 8 is a schematic cross-sectional view showing a portion of themanufacturing processes of the ceramic copper circuit board;

FIG. 9 is a schematic cross-sectional view showing a portion of themanufacturing processes of the ceramic copper circuit board;

FIG. 10 is a schematic cross-sectional view showing a portion of themanufacturing processes of the ceramic copper circuit board; and

FIG. 11 is a schematic cross-sectional view showing a portion of themanufacturing processes of the ceramic copper circuit board.

DETAILED DESCRIPTION

A ceramic copper circuit board according to an embodiment includes aceramic substrate and a first copper part. The first copper part isbonded at a first surface of the ceramic substrate via a first brazingmaterial part. The thickness of the first copper part is 0.6 mm or more.The side surface of the first copper part includes a first slopedportion. The width of the first sloped portion is not more than 0.5times the thickness of the first copper part. The first brazing materialpart includes a first jutting portion jutting from the end portion ofthe first sloped portion. The length of the first jutting portion is notless than 0 μm and not more than 200 μm. The contact angle between thefirst jutting portion and the first sloped portion is 65° or less.

The drawings are schematic and conceptual; and the relationship betweenthe thickness and width of the portions, the proportions of sizes amongportions, etc., are not necessarily the same as the actual values.Furthermore, the dimensions and proportions may be illustrateddifferently among drawings, even for identical portions.

In the specification and drawings, components similar to those describedpreviously are marked with the same reference numerals, and a detaileddescription is omitted as appropriate.

FIGS. 1 and 2 show a structure example of the ceramic copper circuitboard according to the embodiment. FIG. 1 is a schematic cross-sectionalview showing the structure example of the ceramic copper circuit board.FIG. 2 is a schematic cross-sectional view showing a structure exampleof the side surface shapes of the first copper part and the secondcopper part.

In FIGS. 1 and 2, 1 is a ceramic copper circuit board, and 2 is aceramic substrate. 3 a is a first copper part, and 3 b is a secondcopper part. 4 is a back copper plate. 5 a is a first brazing materialpart, and 5 b is a second brazing material part. 6 a is a first juttingportion included in a first brazing material part, and 6 b is a secondjutting portion included in a second brazing material part. 7 is abrazing material layer (a back copper plate-side brazing materiallayer). Also, P is the distance between the first copper part and thesecond copper part. Ta is the thickness of the first copper part. IP1 isa first sloped portion included in the side surface of the first copperpart. Da is the width of the first sloped portion. L1 a is the length ofthe first jutting portion. θ1 a is the contact angle between the firstjutting portion and the first sloped portion. θ2 a is the angle of theupper end portion of the first sloped portion. Tb is the thickness ofthe second copper part. IP2 is a second sloped portion included in theside surface of the second copper part. Db is the width of the secondsloped portion. L1 b is the length of the second jutting portion. θ1 bis the contact angle between the second jutting portion and the secondsloped portion. θ2 b is the angle of the upper end portion of the secondsloped portion. L2 is the length of the removal region. The first copperpart and the second copper part are portions of the circuit pattern. Theback copper plate is provided as a heat dissipation plate. The ceramiccopper circuit board according to the embodiment is not limited to theillustrated configurations. For example, the ceramic copper circuitboard may include three or more copper parts. The back copper plate maybe used as a circuit in the ceramic copper circuit board. The firstcopper part and the second copper part may be separate copper plates ormay be one portion of one copper plate. The shapes of the first copperpart and the second copper part when viewed from above may be variousshapes such as square, rectangular, U-shaped, L-shaped, H-shaped, etc.

The ceramic copper circuit board includes a ceramic substrate, a brazingmaterial part, and a copper part. The copper part is bonded to theceramic substrate via the brazing material part. For example, as shownin FIG. 1, the ceramic substrate 2 includes a first surface S1 and asecond surface S2. The first copper part 3 a is bonded to the firstsurface S1 via the first brazing material part 5 a. The second copperpart 3 b is bonded to the first surface S1 via the second brazingmaterial part 5 b. The copper plate 4 is bonded to the second surface S2via the brazing material layer 7.

An XYZ orthogonal coordinate system is used in the description of theembodiments. A direction connecting the first surface S1 and the secondsurface S2 is taken as a Z-direction. Two mutually-orthogonal directionsperpendicular to the Z-direction are taken as an X-direction and aY-direction. The length L1 a is the length in the X-direction or theY-direction of the first jutting portion. The distance P is the distancein the X-direction or the Y-direction between the first copper part andthe second copper part. The thickness of each component is the length inthe Z-direction of the component.

A silicon nitride substrate, an aluminum nitride substrate, an aluminasubstrate, a zirconia-including alumina substrate, etc., can be used asthe ceramic substrate 2. It is favorable for the three-point bendingstrength of the ceramic substrate 2 to be 500 MPa or more. Some aluminumnitride substrates, some alumina substrates, and some zirconia-includingalumina substrates have three-point bending strengths of 500 MPa orless. Conversely, silicon nitride substrates have high three-pointbending strengths of 500 MPa or more and even 600 MPa or more. When thestrength of the ceramic substrate is high, the TCT characteristics canbe improved even when the thickness Ta and the thickness Tb are set tobe thick and are 0.6 mm or more, and even 0.8 mm or more. For example,the three-point bending strength is measured according to JIS-R-1601(2008). JIS-R-1601 corresponds to ISO 14704 (2000).

The silicon nitride substrate has a thermal conductivity of 50 W/(m·K)or more, or even 80 W/(m·K) or more. For example, the thermalconductivity is measured according to JIS-R-1611 (2010). The JIS-R-1611corresponds to ISO 18755 (2005). In recent years, silicon nitridesubstrates have both a high strength and a high thermal conductivity. Ifthe silicon nitride substrate has a three-point bending strength of 500MPa or more and a thermal conductivity of 80 W/(m·K) or more, thethickness of the ceramic substrate 2 can be thin, i.e., 0.40 mm or less,and even 0.30 mm or less.

Also, aluminum nitride substrates have high thermal conductivity, i.e.,a thermal conductivity of 170 W/(m·K) or more. Because aluminum nitridesubstrates have high thermal conductivities but low strengths, it isdesirable for the substrate thickness to be 0.635 mm or more. Also,alumina substrates and zirconia-including alumina substrates havethermal conductivities of about 20 W/(m·K), but are inexpensive. Also,because the strength is low, a substrate thickness of 0.635 mm isnecessary. Zirconia-including alumina substrates are also called Alusilsubstrates.

The thickness Ta of the first copper part and the thickness Tb of thesecond copper part are 0.6 mm or more. It is favorable for the thicknessTa and the thickness Tb to be 0.8 mm or more. The current-carryingcapacity and the heat dissipation can be improved by setting the copperparts to be thick. The thickness of the first copper part and thethickness of the second copper part may be equal to or different fromthe thickness of the back copper plate 4. When the thickness of thefirst copper part and the thickness of the second copper part are equalto the thickness of the back copper plate 4, the warp amount of thebonded body of the bonding process can be reduced. The number and sizeof the copper parts provided at the first surface S1 side of the ceramicsubstrate 2 are arbitrary.

The first copper part 3 a and the second copper part 3 b are bonded tothe ceramic substrate 2 respectively via the first brazing material part5 a and the second brazing material part 5 b. It is favorable for thefirst brazing material part and the second brazing material part toinclude Ag (silver), Cu (copper), and an active metal. The active metalis at least one element selected from Ti (titanium), Hf (hafnium), Zr(zirconium), or Nb (niobium). A bonding technique that uses a brazingmaterial including Ag, Cu, and an active metal is called active metalbonding.

It is favorable for the active metal to include Ti (titanium). The Tican increase the bonding strength by forming titanium nitride (TiN) byreacting with a nitrogen ceramic. Also, the Ti can increase the bondingstrength by forming titanium oxide (TiO2) by reacting with an oxideceramic. Thus, Ti has good reactivity with the ceramic substrate and canincrease the bonding strength.

Also, it is favorable for each brazing material part to further includeat least one element selected from In (indium), Sn (tin), and C(carbon).

When Ag+Cu+active metal=100 mass %, it is favorable to be within theranges of a content ratio of Ag of 40 to 80 mass %, a content ratio ofCu of 15 to 45 mass %, and a content ratio of Ti of 1 to 12 mass %.Also, when In and Sn are added, it is favorable for the content ratio ofat least one element selected from In or Sn to be in the range of 5 to20 mass %. When C is added, it is favorable for the content ratio of Cto be in the range of 0.1 to 2 mass %. That is, when Ag+Cu+Ti+Sn (orIn)+C=100 mass %, it is favorable to be within the ranges of 40 to 73.9mass % of Ag, 15 to 45 mass % of Cu, 1 to 12 mass % of Ti, 5 to 20 mass% of Sn (or In), and 0.1 to 2 mass % of C. Here, the composition of abrazing material that uses Ti is described, but a portion or all of theTi may be replaced with another active metal. Also, when both In and Snare used as well, it is favorable for the total content to be in therange of 5 to 20 mass %.

As described above, the ceramic copper circuit board has a structure inwhich a copper part is bonded to a ceramic substrate via a brazingmaterial part.

The thickness of the first copper part and the thickness of the secondcopper part are 0.6 mm or more. The side surface of the first copperpart includes the first sloped portion. The side surface of the secondcopper part includes the second sloped portion. The first sloped portionand the second sloped portion are sloped with respect to theZ-direction. The width Da of the first sloped portion satisfiesDa≤0.5Ta. The width Db of the second sloped portion satisfies Db≤0.5Tb.In other words, the width Da and the width Db are lengths in theX-direction or the Y-direction. For example, the first sloped portionand the second sloped portion face each other in the X-direction. Thelength in the X-direction of the first sloped portion is not more than0.5 times the thickness (the length in the Z-direction) of the firstcopper part. The length in the X-direction of the second sloped portionis not more than 0.5 times the thickness of the second copper part.

For example, the upper end of the first sloped portion is continuouswith the upper surface of the first copper part. The lower end of thefirst sloped portion contacts the first brazing material part 5 a (thefirst jutting portion 6 a). The upper end of the second sloped portionis continuous with the upper surface of the second copper part. Thelower end of the second sloped portion contacts the second brazingmaterial part 5 b (the second jutting portion 6 b). The width of eachsloped portion is the dimension in a direction parallel to the firstsurface S1 from the upper end of the sloped portion to the locationwhere the sloped portion and the jutting portion contact. The width ofeach sloped portion can be measured by observing the cross section ofthe ceramic copper circuit board. Also, the width of each sloped portioncan be determined by observing the ceramic copper circuit board fromabove.

By providing a sloped portion in the side surface of each copper part,the thermal stress of the ceramic copper circuit board can be relaxed.On the other hand, a semiconductor element cannot be mounted to thesloped portion. Although the thermal stress can be relaxed when thewidth of the sloped portion is wide, the surface area for mounting thesemiconductor element becomes small. Therefore, it is favorable for thewidth of the sloped portion to be not more than 0.5 times the thicknessof the copper part. More favorably, the width of the sloped portion isnot less than 0.1 times and not more than 0.5 times the thickness of thecopper part. When the width of the sloped portion is less than 0.1 timesthe thickness of the copper part, there is a possibility that the stressrelieving effect may be insufficient because the width of the slopedportion is narrow.

The first brazing material part includes the first jutting portion thatjuts from the end portion of the first copper part. The length L1 a ofthe first jutting portion is not less than 0 μm and not more than 200μm. The second brazing material part includes the second jutting portionthat juts from the end portion of the second copper part. The length L1b of the second jutting portion is not less than 0 μm and not more than200 μm. The thermal stress can be relaxed by causing a portion of thebrazing material part to jut from the end portion of the copper part.Also, it is favorable for the length of each jutting portion to be notless than 0 μm and not more than 200 μm. More favorably, the length ofeach jutting portion is not less than 10 μm and not more than 100 μm.When the length of each jutting portion is greater than 200 μm, therelaxation of the thermal stress is effective, but it is not easy tomake the spacing P between the first copper part and the second copperpart narrow. When the length of each jutting portion is 200 μm or less,the spacing P between the first copper part and the second copper partcan be 2 mm or less, and even 1.5 mm or less.

Also, when the length of each jutting portion becomes less than 0 μm, astate occurs in which the end portion of the brazing material ispositioned further inward than the end portion of the copper part. Thethermal stress relaxation effect is not obtained for such a shape. Also,it is favorable for the thickness of each brazing material part to bewithin the range of 10 to 60 μm.

For example, as illustrated in FIG. 2, the first jutting portion 6 a ispositioned between the first brazing material part 5 a and the secondjutting portion 6 b in the X-direction. The second jutting portion 6 bis positioned between the second brazing material part 5 b and the firstjutting portion 6 a in the X-direction. The length in the X-direction ofthe first jutting portion 6 a is not less than 0 μm and not more than200 jam. The length in the X-direction of the second jutting portion 6 bis not less than 0 μm and not more than 200 μm. To further relax thethermal stress, it is desirable for the length in the X-direction of thefirst jutting portion 6 a to be greater than 0 μm and not more than 200μm. It is desirable for the length in the X-direction of the secondjutting portion 6 b to be greater than 0 μm and not more than 200 μm.

The contact angle θ1 a between the first jutting portion and the firstsloped portion is 65° or less. The contact angle θ1 b between the secondjutting portion and the second sloped portion is 65° or less. By settingthe contact angles θ1 a and θ1 b to be 65° or less, the relaxationeffect of the thermal stress becomes large. More favorably, the contactangles θ1 a and θ1 b are not less than 5° and not more than 60°.

The length L1 a of the first jutting portion, the length L1 b of thesecond jutting portion, the contact angle θ1 a, and the contact angle θ1b are measured using a SEM photograph of a cross section of the ceramiccopper circuit board passing through the first sloped portion, thesecond sloped portion, the first jutting portion, and the second juttingportion. The magnification of the SEM photograph is set to 100 times.Each contact angle and the length of each jutting portion are measuredfrom the SEM photograph. This operation is performed for four differentcross sections, and the average values are used as each contact angleand the length of each jutting portion. It is favorable to use imageanalysis software to perform shape recognition of the jutting portion,the sloped portion, etc., in the SEM photograph.

When the shape of the copper plate when viewed from above is rectangularand the first sloped portion is provided in each side surface, it isfavorable to measure positions that face each other. For example, whenthe copper plate is rectangular, a total of four locations are measuredat opposing positions at the long sides and opposing positions at theshort sides. Also, when multiple copper plates are bonded to one surfaceof the ceramic substrate, each of the copper plates is measured. It ismost favorable for each measurement result to satisfy the rangesdescribed above.

According to the ceramic copper circuit board according to theembodiment, by controlling the width of each sloped portion, the lengthof each jutting portion, and each contact angle, the thermal stress canbe relaxed while ensuring the surface area where the semiconductorelements are mounted. Therefore, the power density of the semiconductormodule can be increased.

It is favorable for the angle θ2 a of the upper end portion of the firstsloped portion to be 50° or more. It is favorable for the angle θ2 b ofthe upper end portion of the second sloped portion to be 50° or more.FIGS. 3 and 4 are schematic cross-sectional views showing otherstructure examples of the side surface shapes of the first copper partand the second copper part. In FIGS. 3 and 4, components that aresubstantially similar to the components shown in FIGS. 1 and 2 aremarked with the same reference numerals.

FIG. 2 illustrates a structure when the angle θ2 a of the upper endportion of the first sloped portion is obtuse and the angle θ2 b of theupper end portion of the second sloped portion is obtuse. FIG. 3illustrates a structure when each upper end portion has a rounded shape.FIG. 4 illustrates a structure when the angle of each upper end portionis acute. In FIGS. 2 and 3, the angle of each upper end portion is 65°or more. In FIG. 4, the angle of each upper end portion is less than50°. The SEM photograph (the magnification of 100 times) described aboveis used also when measuring the angle of each upper end portion. Here,obtuse means that the angle is not less than 90° but less than 180°.Acute means that the angle is less than 90°. A rounded shape means thata curved surface is observed at the corner of the upper end portion in aSEM photograph having a magnification of 100 times.

To increase the surface area where the semiconductor elements aremounted, it is favorable for the upper surface end portion of the firstcopper part and the upper surface end portion of the second copper partto be flat. Therefore, the structures illustrated in FIGS. 2 and 4 arefavorable. Also, when each upper end portion has a rounded shape asillustrated in FIG. 3, it is desirable for the rounded shape to begradual.

When resin-molding is performed, it is favorable for each upper endportion to have the shapes illustrated in FIGS. 2 and 3. Resin-moldingis the process of sealing with a resin after the semiconductor elementsare mounted. By resin-molding, the insulation properties can beimproved, and the degradation due to moisture, etc., can be prevented.When the angle of each upper end portion is an acute angle that is lessthan 50° or even 45° or less, there is a possibility that the resin maynot penetrate onto the first sloped portion and onto the second slopedportion. Bubbles form at locations to which the mold resin does notappropriately penetrate. Therefore, the yield of the resin-moldingdecreases. In recent years, mold processes such as transfer molding,etc., in which the suitability for mass production is excellent havebeen developed. In transfer molding, a method is used in which a resinis injected into a mold. Because the resin is caused to flow through themold, it is favorable to use a structure in which small gaps do noteasily form. Also, bubbles easily cause detachment of the mold resinwhen thermal stress is applied. When the mold resin detaches, thiscauses a conduction defect, an insulation defect, etc. Therefore, it isfavorable for the angles θ2 a and θ2 b to be 50° or more, and morefavorably 55° or more. More favorably, the angles θ2 a and θ2 b are 75°or more.

A method for measuring the angles θ2 a and θ2 b will now be described.FIGS. 5A, 5B, and 5C are drawings showing a method for measuring theupper end portion of the first sloped portion and the angle of the upperend portion of the second sloped portion. The angle θ2 a is determinedby calculating the angle at the point where a line Li1 and a line Li2cross. The line Li1 is a line extending along the flat surface of theupper surface of the first copper part 3 a in a SEM photograph of thecross section. The line Li2 is a line extending from the location atwhich the side surface of the first copper part 3 a starts to slopedownward (toward the ceramic substrate side). The angle θ2 b isdetermined by calculating the angle at the point where a line Li3 and aline Li4 cross. The line Li3 is a line extending along the flat surfaceof the upper surface of the second copper part 3 b in the SEM photographof the cross section. The line Li4 is a line extending from the locationat which the side surface of the second copper part 3 b starts to slopedownward (toward the ceramic substrate side).

FIG. 5A shows an example in which the upper end portion of the firstsloped portion meets the upper surface of the first copper part. FIGS.5B and 5C show examples in which the portion at which the upper surfaceof the first copper part and the upper end portion of the first slopedportion are connected has a rounded shape. In FIG. 5C, the first slopedportion is sloped to be slightly recessed inward. Specifically, in FIG.5C, the first sloped portion is recessed inward in a circular arc-likeconfiguration. A slight unevenness may be provided in the first slopedportion.

FIG. 6 is a schematic cross-sectional view showing another structureexample of the side surface shapes of the first copper part and thesecond copper part. FIG. 6 illustrates shapes in which unevennessesexist in the first sloped portion and the second sloped portion. InFIGS. 6, 2 is the ceramic substrate. 3 a is the first copper part, and 3b is the second copper part. 5 a is the first brazing material part, and5 b is the second brazing material part. IP1 is the first slopedportion, and IP2 is the second sloped portion. Small unevennesses areformed in the first sloped portion IP1 and the second sloped portion IP2shown in FIG. 6. The existence or absence of the unevenness in eachsloped portion can be confirmed using a cross section SEM photograph inwhich the side surface of the first copper part and the side surface ofthe second copper part are enlarged 1000 times. It is considered that anunevenness exists in each sloped portion when a micro unevenness isobserved in the first sloped portion and the second sloped portion shownin an enlarged photograph (1000 times). It is favorable for the heightdifference between a protrusion and a recess that are adjacent to eachother to be not less than 1 μm and not more than 20 μm. Also, it isfavorable for multiple micro recesses and multiple micro protrusions toexist alternately. A micro wavy shape is formed when micro unevennessesare alternately provided.

Also, when the first sloped portion and the second sloped portion haveshapes that start to slope by being recessed slightly inward, it isfavorable for the width of the portion that is recessed inward to be notmore than ¼ of the width of the first sloped portion or the width of thesecond sloped portion. Such a recessed structure is called a microrecessed configuration.

When a micro uneven configuration or a micro recessed configuration isprovided, the adhesion between the mold resin and each copper part canbe improved. That is, the TCT characteristics of the ceramic coppercircuit board can be improved, and the adhesion between the ceramiccopper circuit board and the mold resin can be improved. On the otherhand, when the size of the uneven configuration and/or the recessedconfiguration is large, bubbles easily form between the mold resin andeach copper part.

FIG. 7 are schematic plan views showing structure examples of theceramic copper circuit board. FIG. 7A illustrates a structure in which acopper plate that includes the first copper part 3 a and another copperplate that includes the second copper part 3 b are bonded to the ceramicsubstrate 2. FIG. 7B illustrates a structure in which one copper platethat includes the first copper part 3 a and the second copper part 3 bis bonded to the ceramic substrate 2. In either structure as well, thefirst copper part and the second copper part are separated from eachother in one horizontal direction along the bonding surface of theceramic substrate. For example, the first sloped portion IP1 of thefirst copper part faces the second sloped portion IP2 of the secondcopper part in the one direction.

It is favorable for 90% or more of the side surface of the coppercircuit board on which the semiconductor element is mounted to have theshapes described above. For example, multiple copper circuit boards onwhich the semiconductor elements are mounted are provided for theceramic substrate. The first copper part is one of the multiple coppercircuit boards. The second copper part is another one of the multiplecopper circuit boards. Or, the first copper part may be a portion of onecopper circuit board, and the second copper part may be another portionof the one copper circuit board. It is desirable for 90% or more of theside surface of the first copper part to have a shape similar to thefirst sloped portion described above. Also, it is desirable for 90% ormore of the side surface of the second copper part to have a shapesimilar to the second sloped portion described above. Most favorably,the entire side surface of the first copper part has a shape similar tothe first sloped portion, and the entire side surface of the secondcopper part has a shape similar to the second sloped portion.

A ceramic copper circuit board such as those described above hasexcellent TCT characteristics.

For example, in one cycle of TCT, holding for 30 minutes at −40° C.,holding for 10 minutes at room temperature, holding for 30 minutes at175° C., and holding for 10 minutes at room temperature are sequentiallyperformed. The cycles are repeated, and the number of cycles at which adiscrepancy occurs in the ceramic copper circuit board is measured.Discrepancies of the circuit board are, for example, detachment of thebrazing material parts (5 a and 5 b), detachment of the brazing materiallayer 7, a crack of the ceramic substrate 2, etc.

The ceramic copper circuit board of the embodiment can have excellentTCT characteristics even when the high-temperature-side holdingtemperature of the TCT is 175° C. or more. A holding temperature that is175° C. or more is, for example, 200° C. to 250° C. In a semiconductorelement such as a SiC element, a GaN element, etc., the junctiontemperature is predicted to become 200 to 250° C. The junctiontemperature corresponds to the guaranteed operating temperature of thesemiconductor element. Therefore, in the ceramic copper circuit board aswell, durability at high temperatures is desirable.

Also, by controlling the width of each sloped portion and the length ofeach jutting portion, stress relaxation can be performed by a smalljutting portion. Therefore, the spacing P between the first copper partand the second copper part can be made narrow, i.e., 2 mm or less, oreven 1.5 mm or less.

Also, by controlling the shape of the upper end portion of each slopedportion, the mounting surface area of the semiconductor element and theimprovement of the resin moldability can be ensured.

A method for manufacturing the ceramic copper circuit board according tothe embodiment will now be described. As long as the ceramic coppercircuit board according to the embodiment has the configurationdescribed above, the ceramic copper circuit board is not limited to thefollowing manufacturing method. For example, according to the followingmanufacturing method, the yield of the ceramic copper circuit boardaccording to the embodiment can be increased.

First, a bonded body is prepared in which the first copper part and thesecond copper part are bonded to at least one surface of a ceramicsubstrate via a brazing material layer. The thickness of the firstcopper part and the thickness of the second copper part are 0.6 mm ormore. The first copper part and the second copper part have circuitpattern shapes. The first copper part and the second copper part may becircuit patterns that are separated from each other or may be a portionof one circuit pattern. The first copper part and the second copper partare formed by etching one copper plate. Or, the first copper part andthe second copper part may be formed by bonding, to the ceramicsubstrate, a copper plate that includes the first copper part andanother copper plate that includes the second copper part. A method isfavorable in which copper plates are bonded to two surfaces of theceramic substrate, and the first copper part and the second copper partare formed by etching-patterning the copper plate of at least onesurface. Bonding copper plates to two surfaces can suppress theoccurrence of warp of the bonded body. Also, in the case where etchingis used, it is possible to form any pattern shape. When viewed fromabove, the shapes of the first copper part and the second copper partare arbitrary, and various shapes such as, for example, square,rectangular, U-shaped, L-shaped, H-shaped, etc., may be used. Thebrazing material layer is provided between the first copper part and thesecond copper part.

The method for manufacturing the ceramic copper circuit board accordingto the embodiment includes a brazing material etching process and acopper etching process. The method for manufacturing the ceramic coppercircuit board according to the embodiment may further include apreparation process and a circuit pattern formation process.

In the preparation process, a bonded body is prepared in which a copperplate having a thickness of 0.6 mm or more is bonded to at least onesurface of the ceramic substrate via a brazing material layer. In thecircuit pattern formation process, the copper plate is etched into apattern shape. The first copper part and the second copper part areformed thereby. In the brazing material etching process, the brazingmaterial layer that exists between the first copper part and the secondcopper part is etched. By etching the brazing material layer, the firstbrazing material part that is positioned between the ceramic substrateand the first copper part is formed, and the second brazing materialpart that is positioned between the ceramic substrate and the secondcopper part is formed. At this time, the etching is performed so thatthe length L2 of the removal region is within the range of ±100 μm fromthe end portion of the copper part. For example, the length of theremoval region of the first brazing material part is the distance in adirection parallel to the ceramic substrate front surface between theend portion of the first copper part and the end portion of the firstbrazing material part most proximate to the end portion of the firstcopper part. The length of the removal region of the second brazingmaterial part is the distance in a direction parallel to the ceramicsubstrate front surface between the end portion of the second copperpart and the end portion of the second brazing material part mostproximate to the end portion of the second copper part. In the copperetching process, the side surface of the first copper part and the sidesurface of the second copper part are etched. At this time, etching isperformed so that the length L1 a of the first jutting portion and thelength L1 b of the second jutting portion are within the range not lessthan 0 μm and not more than 200 μm, the contact angle θ1 a between thefirst jutting portion and the first sloped portion and the contact angleθ1 b between the second jutting portion and the second sloped portionare 65° or less, the width Da of the first sloped portion satisfiesDa≤0.5Ta, and the width Db of the second sloped portion satisfiesDb≤0.5Tb. Also, it is favorable for the length L1 a of the first juttingportion and the length L1 b of the second jutting portion to be greaterthan 0 μm.

FIGS. 8 to 11 are schematic cross-sectional views showing a portion ofthe manufacturing processes of the ceramic copper circuit board. FIGS. 8to 11 illustrate the flow of the manufacturing processes of the ceramiccopper circuit board. In FIGS. 8 to 11, components that aresubstantially similar to the components shown in FIGS. 1 and 2 aremarked with the same reference numerals. L2 of FIG. 10 is the length ofthe removal region. In FIG. 8, a bonded body in which copper plates arebonded to two surfaces is described as an example. The bonded body ofFIG. 8 is a bonded body that uses so-called blanket copper plates.

First, a preparation process of preparing the bonded body is performed.The bonded body has a copper plate having a thickness of 0.6 mm or morebonded to at least one surface of the ceramic substrate via a brazingmaterial layer. The ceramic substrate and the copper plate are bondedusing active metal bonding.

The ceramic substrate can include a silicon nitride substrate, analuminum nitride substrate, an alumina substrate, a zirconia-includingalumina substrate, etc. It is favorable for the three-point bendingstrength of the ceramic substrate 2 to be 500 MPa or more. It isfavorable for the thickness T of the copper plate to be 0.6 mm or more.The thickness of a front copper plate 3 may be equal to or differentfrom the thickness of the back copper plate 4. The warp of the bondedbody is suppressed when the thickness of the front copper plate 3 andthe thickness of the back copper plate 4 is the same. It is favorablefor the lengthwise and crosswise size of the copper plate to be about0.5 to 5 mm smaller than the ceramic substrate.

The brazing material layers 5 and 7 include a brazing material includingAg, Cu, and an active metal. One, two, or more selected from Sn, In, orC may be added to the brazing material as necessary. The bonding processis performed at a temperature of 700 to 880° C. in a vacuum (10-2 Pa orless).

A bonded body of a ceramic substrate and a copper plate such as thatshown in FIG. 8 is made by this process.

Then, a circuit pattern formation process of etching the copper plateinto a pattern shape is performed. In this process, a circuit pattern isformed in the copper plate of the bonded body (the bonded body of theceramic substrate and the copper plate). Here, an example is describedin which a circuit pattern is formed in the front copper plate. When acircuit pattern is formed in the back copper plate as well, a similarprocess is performed also for the back copper plate.

First, an etching resist is coated onto the portion of the front copperplate 3 that will remain as the circuit pattern. Subsequently, thecopper plate is etched. It is favorable to use iron chloride or copperchloride in the etching process of the copper plate. It is favorable forthe iron chloride to be FeCl3. It is favorable for the copper chlorideto be CuCl2. An etchant that includes iron chloride or copper chloridecan selectively etch the copper plate. In other words, the active metalbrazing material layer can remain substantially without being etched. Bythis process, the copper plate 3 is etched as shown in FIG. 9, and thefirst copper part 3 a and the second copper part 3 b are formed. At thistime, the etching is performed so that the first sloped portion isformed in the side surface of the first copper part 3 a, and the secondsloped portion is formed in the side surface of the second copper part 3b.

In this process, it is favorable to set the distance P between the firstcopper part 3 a and the second copper part 3 b to be in the range of 0μm to −200 μm with respect to the final distance P between the firstcopper part 3 a and the second copper part 3 b by considering the lengthof the jutting portion formed in a subsequent process. For example, whenthe final distance P between the first copper part 3 a and the secondcopper part 3 b is 1.5 mm, it is favorable to set the distance P in thecircuit pattern formation process to be within the range of 1.5 to 1.3mm. That is, it is favorable to preset the distance P directly after thecircuit pattern formation process to be equal to the final distance P ornot more than 200 μm smaller than the final distance P. Also, etching isperformed so that the width Da of the first sloped portion and thethickness Ta of the first copper part satisfy Da≤(0.5Ta+100 μm) and thewidth Db of the second sloped portion and the thickness Tb of the secondcopper part satisfies Db≤(0.5Tb+100 μm). By controlling the shapebeforehand as described above in the circuit pattern formation process,the shape control in the subsequent processes becomes easy.

Although FIG. 9 shows an example in which the copper plate ispatternized into two (the first copper part and the second copper part),the pattern shape that is formed is modifiable as appropriate. Also, inthis process as shown in FIG. 9, a portion of a brazing material layer 5exists between the first copper part 3 a and the second copper part 3 b.The portion of the brazing material layer 5 is not covered with thecopper parts and is exposed.

Then, a brazing material etching process is performed. In the brazingmaterial etching process, the length L2 of the removal region is causedto be within the range of ±100 μm of the copper part end portion byetching the brazing material layer existing between the first copperpart and the second copper part. Due to the brazing material etchingprocess, the brazing material that is between the ceramic substrate andthe first copper part is electrically isolated from the brazing materialbetween the ceramic substrate and the second copper part.

In the brazing material etching process, the brazing material layer isetched using aqueous hydrogen peroxide, an ammonium compound, etc. Abrazing material etchant that includes aqueous hydrogen peroxide, anammonium compound, or the like is effective when the brazing materiallayer is an active metal brazing material that includes Ag, Cu, and anactive metal, etc. Such a brazing material etchant can selectively etchthe active metal brazing material layer. Also, the brazing materialetchant may include a component other than aqueous hydrogen peroxide oran ammonium compound as necessary. Also, the brazing material etchantmay include a mixed liquid of aqueous hydrogen peroxide and an ammoniumcompound.

The brazing material layer is etched so that the length L2 of theremoval region is within the range of ±100 μm. The length L2 of theremoval region is the distance between one end of the copper part andone end of the brazing material part. By setting the length L2 of theremoval region to be within the range described above, the shape controlin the subsequent processes becomes easy.

The state in which one end of the copper part overlaps one end of thebrazing material part in the Z-direction corresponds to the state inwhich the jutting portion length L1 is 0 μm. The state in which thelength L2 of the removal region is ±100 μm corresponds to the state inwhich the jutting portion length L1 is within the range of ±100 μm. Anegative length L2 of the removal region means that the brazing materialpart is positioned further inward than the copper part end portion. Inother words, this means that the brazing material part does not jut fromthe copper part end portion. Also, a positive length L2 of the removalregion means that the brazing material part is positioned outward of thecopper part end portion. In other words, this means that the brazingmaterial part juts from the copper part end portion. That is, the lengthL2 of the removal region being −100 μm is the state in which the brazingmaterial is removed in the range of 100 μm inward of the copper part endportion. Also, the length L2 of the removal region being +100 μm is thestate in which the jutting portion is formed 100 μm outward of thecopper part end portion.

Also, it is favorable for the length L2 of the removal region to be inthe range of −50 μm to +30 μm. The jutting portion length L1 that isfavorable for ensuring the insulation distance is not less than 10 μmand not more than 100 μm. The jutting portion length L1 is controlledeasily in subsequent processes by setting the length L2 of the removalregion to be ±100 μm, and more easily within the range of −50 μm to +30μm.

Then, a copper etching process of etching the side surface of the firstcopper part and the side surface of the second copper part is performed.In this process, the etching is performed so that the length L1 a of thefirst jutting portion and the length L1 b of the second jutting portionare in the range not less than 0 μm and not more than 200 μm, thecontact angle θ1 a between the first jutting portion and the firstsloped portion is 65° or less, the contact angle θ1 b between the secondjutting portion and the second sloped portion is 65° or less, the widthof the first sloped portion is not more than 0.5 times the thickness ofthe first copper part, and the width of the second sloped portion is notmore than 0.5 times the thickness of the second copper part.

By using a liquid to etch the copper, the length of each jutting portioncan be controlled by etching the side surface of the first copper partand the side surface of the second copper part. Also, the contact angleθ1 a, the contact angle θ1 b, the angle θ2 a of the upper end portion ofthe first sloped portion, and the angle θ2 b of the upper end portion ofthe second sloped portion can be controlled by etching the side surfaceof the first copper part and the side surface of the second copper part.Also, when it is desirable not to etch a region of the upper surface orthe side surface of the first copper part or the second copper part, itis effective to use a resist beforehand that is resistant to the etchant(a mixed liquid of aqueous hydrogen peroxide and an ammonium compound,etc.) used in the process of etching the brazing material layer. It isalso effective to newly coat a resist in the region that is not to beetched after the process of etching the brazing material layer.

Also, the etching conditions of the side surface of the first copperpart and the side surface of the second copper part are such that theshape of the ceramic copper circuit board according to the embodimentdescribed above is satisfied. That is, the etching is performed so thatthe width of the first sloped portion, the width of the second slopedportion, the length of the first jutting portion, the length of thesecond jutting portion, the shape of the first sloped portion, and theshape of the second sloped portion are similar to those of theconfiguration of the ceramic copper circuit board according to theembodiment described above.

It is favorable for the side surface of the first copper part and theside surface of the second copper part to be etched using conditionssuch that the etching rate of the first and second copper parts is 100μm or less in one etching process. The etching rate is the amount thateach copper part is etched in one etching process. The etching rate iscalculated from “the thickness of the copper part before the etching—thethickness of the copper part after the etching”. The etchant for thecopper part includes iron chloride or copper chloride. It is favorablefor the conditions of one etching process to provide an etching rate of100 μm or less in 1 to 10 minutes. Also, it is favorable for the etchingrate to be 40 to 60 μm. It is favorable for the etching time to bewithin the range of 1 to 4 minutes. When the etching rate is less than40 μm, the etching time lengthens, and the suitability for massproduction decreases. Also, when the etching rate is large and isgreater than 100 μm, the control of the shape of the first slopedportion and the shape of the second sloped portion becomes difficult.

Also, a chemical polishing liquid that is a mixed liquid of sulfuricacid and hydrogen peroxide can be used as the etchant for the copperpart. However, generally, the etching rate of a chemical polishingliquid is less than the etching rate of an etchant using iron chlorideor copper chloride. That is, when performing etching for the same amountof time, the etching amount is higher for a copper plate etchant usingiron chloride or copper chloride. The suitability for mass productiondecreases as the etching time lengthens. Therefore, it is favorable touse iron chloride or copper chloride as the etchant.

The same etchant can be used in the circuit pattern formation processand the copper etching process. When the same etchant is used in thecircuit pattern formation process and the copper etching process, it isfavorable for the etching time of the copper etching process to be lessthan the etching time of the circuit pattern formation process. By usingthe same etchant, the etching rate can be controlled using the time.

In the ceramic copper circuit board according to the embodiment, thecopper plate thickness T is 0.6 mm or more. It is favorable for theetching rate of one etching process to be 100 μm or less, and morefavorably 40 to 60 μm. Also, it is favorable for the etching time to be1 to 10 minutes, and more favorably 1 to 4 minutes. By using suchconditions, the suitability for mass production also can be improvedwith a high yield and with control of the shape. Also, the brazingmaterial layer etching and the copper etching process may be performedalternately multiple times. Thereby, the width of each sloped portion,the length of each jutting portion, and each contact angle are easilycontrolled to be within the ranges described above.

An example is described above in which both the length L1 a and thelength L1 b of the ceramic copper circuit board are not less than 0 μmand not more than 200 μm. Only one of the length L1 a or the length L1 bmay be not less than 0 μm and not more than 200 μm. To further relax thethermal stress, it is desirable for both the length L1 a and the lengthL1 b to be not less than 0 μm and not more than 200 μm.

Also, only one of the contact angle θ1 a or the contact angle θ1 b maybe 65° or less. However, to further relax the thermal stress, it isfavorable for both the contact angle θ1 a and the contact angle θ1 b tobe 65° or less.

Also, only one of the width Da being not more than 0.5 times thethickness Ta or the width Db being not more than 0.5 times the thicknessTb may be satisfied. However, to further increase the mounting area ofthe semiconductor element, it is favorable for both the width Da beingnot more than 0.5 times the thickness Ta and the width Db being not morethan 0.5 times the thickness Tb to be satisfied.

Also, only one of the angle θ2 a or the angle θ2 b may be 50° or more.However, to further improve the resin moldability, it is favorable forboth the angle θ2 a and the angle θ2 b to be 50° or more.

EXAMPLES Examples 1 to 15 and Comparative Examples 1 to 2

Bonded bodies of the ceramic substrate and the copper plate wereprepared as shown in Table 1. For the ceramic substrate, a siliconnitride substrate (having a thermal conductivity of 90 W/(m·K) and athree-point bending strength of 650 MPa) that was 60 mm long×50 mmwide×0.32 mm thick was used as a first silicon nitride substrate. Also,a silicon nitride substrate (having a thermal conductivity of 85 W/(m·K)and a three-point bending strength of 700 MPa) that was 60 mm long×50 mmwide×0.25 mm thick was used as a second silicon nitride substrate. Also,an aluminum nitride substrate (having a thermal conductivity of 170W/(m·K) and a three-point bending strength of 400 MPa) that was 60 mmlong×50 mm wide×0.635 mm thick was prepared. Also, the copper plate wasoxygen-free copper that was 55 mm long×45 mm wide. The bonding methodwas bonding by active metal bonding. Also, a copper plate that had thesame size front and back was bonded.

TABLE 1 SILICON NITRIDE COPPER PLATE BRAZING MATERIAL LAYER SUBSTRATETHICKNESS T(mm) THICKNESS (μm) COMPONENTS (wt %) BONDED BODY 1 FIRSTSILICON 0.6 30 Ag (57)—Cu (30)—Sn(10)—Ti (3) NITRIDE SUBSTRATE BONDEDBODY 2 FIRST SILICON 0.8 40 Ag (49.7)—Cu (30)—Sn (12)—Ti (8)—C (0.3)NITRIDE SUBSTRATE BONDED BODY 3 FIRST SILICON 1.0 45 Ag (48.8)—Cu(35)—Sn (10)—Ti (6)—C (0.2) NITRIDE SUBSTRATE BONDED BODY 4 SECONDSILICON 0.9 35 Ag (49.7)—Cu (30)—Sn (12)—Ti (8)—C (0.3) NITRIDESUBSTRATE BONDED BODY 5 SECOND SILICON 1.0 45 Ag (48.8)—Cu (35)—Sn(10)—Ti (6)—C (0.2) NITRIDE SUBSTRATE BONDED BODY 6 SECOND SILICON 0.640 Ag (57)—Cu (30)—Sn (10)—Ti (3) NITRIDE SUBSTRATE

Then, an etching resist was coated onto the front copper plate of thebonded body. The etching resist was a commercial resist that canwithstand the liquid used to etch the brazing material layer, and wascoated in a pattern shape. The design was such that the spacing betweenthe patterns after etching the copper plate was 1.0 mm.

Then, the copper plate was etched. One copper plate was subdivided intomultiple copper parts corresponding to the circuit pattern by theetching. The distance P between the adjacent copper parts was 1.0 mm.Also, the etching was performed so that a width D of the sloped portionof the copper part side surface and the thickness T of the copper partsatisfied D≤(0.5T+100 μm). Also, the brazing material layer was exposedbetween the adjacent copper parts.

Then, the brazing material layer was etched. The etching of the brazingmaterial layer was performed to prepare bonded bodies having the lengthsL2 of the removal regions of Table 2. In the examples, the length L2 ofthe removal region was in the range of ±100 μm. The lengths L2 of theremoval regions in Table 2 that are listed as negative show how much thebrazing material layer is removed from the copper part end portion.

Also, in a comparative example 1, the brazing material layer greatlyjuts. In a comparative example 2, the length L2 of the removal region islarge.

TABLE 2 REMOVAL REGION BONDED BODY LENGTH L2 (μM) EXAMPLE 1 BONDED BODY1 0 EXAMPLE 2 BONDED BODY 1 −50 EXAMPLE 3 BONDED BODY 1 −100 EXAMPLE 4BONDED BODY 1 +60 EXAMPLE 5 BONDED BODY 2 0 EXAMPLE 6 BONDED BODY 2 −50EXAMPLE 7 BONDED BODY 2 −100 EXAMPLE 8 BONDED BODY 2 +50 EXAMPLE 9BONDED BODY 3 0 EXAMPLE 10 BONDED BODY 3 −50 EXAMPLE 11 BONDED BODY 3−100 EXAMPLE 12 BONDED BODY 3 +30 EXAMPLE 13 BONDED BODY 4 −60 EXAMPLE14 BONDED BODY 4 −90 EXAMPLE 15 BONDED BODY 5 −80 EXAMPLE 16 BONDED BODY6 +20 EXAMPLE 17 BONDED BODY 6 −100 COMPARATIVE BONDED BODY 1 +200EXAMPLE 1 COMPARATIVE BONDED BODY 1 −300 EXAMPLE 2 COMPARATIVE BONDEDBODY 6 −300 EXAMPLE 3

Then, an etching process of the copper part side surface was performedfor the ceramic copper circuit boards according to the examples and thecomparative examples. Ceramic copper circuit boards that had the shapesof Table 3 were made thereby. The copper etching process used a ferricchloride solution for an etching time 3 minutes to provide an etchingrate 60 μm. Also, the etching amount was controlled by adjusting thetimes of the circuit pattern formation process and the copper etchingprocess.

TABLE 3 SLOPED SLOPED JUTTING PORTION PORTION PORTION CONTACT UPPER ENDWIDTH LENGTH ANGLE PORTION ANGLE D (mm) D ≤ 0.5 T L1 (μm) θ1 (°) θ2 (°)EXAMPLE 1 0.15 D ≤ 0.3 84 30 84 EXAMPLE 2 0.15 D ≤ 0.3 45 40 79 EXAMPLE3 0.1 D ≤ 0.3 28 60 55 EXAMPLE 4 0.2 D ≤ 0.3 150 20 95 EXAMPLE 5 0.25 D≤ 0.4 81 20 93 EXAMPLE 6 0.2 D ≤ 0.4 66 40 89 EXAMPLE 7 0.15 D ≤ 0.4 3150 68 EXAMPLE 8 0.3 D ≤ 0.4 110 15 99 EXAMPLE 9 0.3 D ≤ 0.4 78 10 103EXAMPLE 10 0.25 D ≤ 0.5 57 30 92 EXAMPLE 11 0.2 D ≤ 0.5 43 40 81 EXAMPLE12 0.4 D ≤ 0.5 95 5 108 EXAMPLE 13 0.2 D ≤ 0.4 53 35 85 EXAMPLE 14 0.3 D≤ 0.4 65 40 85 EXAMPLE 15 0.4 D ≤ 0.5 75 45 95 EXAMPLE 16 0.1 D ≤ 0.3120 50 75 EXAMPLE 17 0.2 D ≤ 0.3 70 55 85 COMPARATIVE 0.43 D ≤ 0.3 +33080 70 EXAMPLE 1 COMPARATIVE 0.15 D ≤ 0.3 −165 50 45 EXAMPLE 2COMPARATIVE 0.1 D ≤ 0.1 50 80 50 EXAMPLE 3

In the ceramic copper circuit boards according to the examples, thewidth of the sloped portion, the length of the jutting portion, thecontact angle, the angle of the sloped portion upper end portion, etc.,were in the desirable ranges. Also, a micro uneven configuration thatwas not less than 1 μm and not more than 20 μm or a micro recessedconfiguration that was not more than ¼ of the width D was observed inthe sloped portion for the ceramic copper circuit boards according tothe examples.

Also, in the comparative example 1, the width D of the sloped portionwas large, and the length L1 of the jutting portion also was undesirablylarge. Even when etching-patterning of the copper plate side surface wasperformed after pre-forming the jutting portion, it was difficult topattern into the target shape. Also, when the length L2 of the removalregion was increased as in the comparative example 2, it was difficultto pattern into the target shape even when etching-patterning of thecopper plate side surface was performed.

The TCT test and the resin moldability were verified for the ceramiccopper circuit boards according to the examples and the comparativeexamples.

One cycle of the TCT test was set to hold at −40° C.×30 minutes→hold atroom temperature×10 minutes→hold at 250° C.×30 minutes→hold at roomtemperature×10 minutes. For the silicon nitride copper circuit boards,the existence or absence of the occurrence of discrepancies in theceramic copper circuit board after 3000 cycles was verified. Also, forthe aluminum nitride copper circuit board, the existence or absence ofthe occurrence of discrepancies in the ceramic copper circuit boardafter 2000 cycles was verified. For the existence or absence of theoccurrence of discrepancies, the existence or absence of cracks betweenthe ceramic substrate and the copper part was verified using ultrasonictest equipment (SAT). The state of cracks not being observed is notatedas good, and cracks being observed is notated as no good.

Also, for the resin moldability, a semiconductor module that wasresin-molded by transfer molding was made. The existence or absence ofbubbles at the copper part side surface of the semiconductor module wasobserved. The existence or absence of bubbles was performed by CTobservation. Bubbles being not more than 2% of the copper part sidesurface by area ratio is displayed as good, and being greater than 2% isdisplayed as no good.

The results are shown in Table 4.

TABLE 4 TCT RESIN TEST MOLDABILITY EXAMPLE 1 GOOD GOOD EXAMPLE 2 GOODGOOD EXAMPLE 3 GOOD NO GOOD EXAMPLE 4 GOOD GOOD EXAMPLE 5 GOOD GOODEXAMPLE 6 GOOD GOOD EXAMPLE 7 GOOD GOOD EXAMPLE 8 GOOD GOOD EXAMPLE 9GOOD GOOD EXAMPLE 10 GOOD GOOD EXAMPLE 11 GOOD GOOD EXAMPLE 12 GOOD GOODEXAMPLE 13 GOOD GOOD EXAMPLE 14 GOOD GOOD EXAMPLE 15 GOOD GOOD EXAMPLE16 GOOD GOOD EXAMPLE 17 GOOD GOOD COMPARATIVE NO GOOD GOOD EXAMPLE 1COMPARATIVE NO GOOD NO GOOD EXAMPLE 2 COMPARATIVE NO GOOD NO GOODEXAMPLE 3

It can be seen from the Table that the ceramic copper circuit boardsaccording to the examples had excellent TCT characteristics. Also, theTCT characteristics were good even when the thickness of the ceramicsubstrate was thin, i.e., 0.25 mm, as in the examples 13 to 15.

On the other hand, the TCT characteristics degraded when a contact angleθ1 between the jutting portion and the sloped portion of the copper partside surface was large, i.e., 80°, as in the comparative example 1 andthe comparative example 3. The TCT characteristics of the comparativeexample 2 degraded because the jutting portion length L1 was −100 μm.

Also, the resin moldability was good when an angle θ2 of the upper endportion of the sloped portion was 55° or more. For less than 65° as inthe example 1 and the comparative example 2, bubbles formed easily.

Also, conduction defects occurred more easily when the jutting portionlength L1 was large, i.e., greater than 200 μm, as in the comparativeexample 1. Therefore, it is difficult to reduce the distance P betweenthe copper parts.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the invention. The above embodiments can be practiced incombination with each other.

What is claimed is:
 1. A ceramic copper circuit board, comprising: aceramic substrate; and a first copper part bonded to a first surface ofthe ceramic substrate via a first brazing material part, a thickness ofthe first copper part being 0.6 mm or more, a side surface of the firstcopper part including a first sloped portion, a width of the firstsloped portion being not more than 0.5 times the thickness of the firstcopper part, the first brazing material part including a first juttingportion jutting from an end portion of the first sloped portion, alength of the first jutting portion being not less than 0 μm and notmore than 200 μm, a contact angle between the first jutting portion andthe first sloped portion being not less than 5° and not more than 65°,and an angle of an upper end portion of the first sloped portion beingless than 50°.
 2. The ceramic copper circuit board according to claim 1,wherein the contact angle is not more than 60°.
 3. The ceramic coppercircuit board according to claim 1, wherein the length of the firstjutting portion is greater than 0 μm and not more than 200 μm.
 4. Theceramic copper circuit board according to claim 1, wherein the firstbrazing material part includes silver, copper, and an active metal. 5.The ceramic copper circuit board according to claim 1, wherein thethickness of the first copper part is 0.8 mm or more, the ceramicsubstrate is a silicon nitride substrate, and a thickness of the ceramicsubstrate is 0.4 mm or less.
 6. The ceramic copper circuit boardaccording to claim 1, further comprising: a second copper part bonded tothe first surface via a second brazing material part, the second copperpart being separated from the first copper part in a first directionalong the first surface, a distance in the first direction between atleast a portion of the first copper part and at least a portion of thesecond copper part being 2 mm or less.
 7. The ceramic copper circuitboard according to claim 1, wherein the contact angle is not less than5° and not more than 60°, the length of the first jutting portion isgreater than 0 μm and not more than 200 μm, the thickness of the firstcopper part is 0.8 mm or more, the ceramic substrate is a siliconnitride substrate, and a thickness of the ceramic substrate is 0.4 mm orless.
 8. The ceramic copper circuit board according to claim 1, whereinthe length of the first jutting portion is greater than 40 μm and notmore than 200 μm.